Insufficient sleep cycle -- especially for shift workers -- may increase heart disease risk

http://www.eurekalert.org/pub_releases/2016-06/aha-isc060116.php

Public Release: 6-Jun-2016
Insufficient sleep cycle -- especially for shift workers -- may increase heart disease risk
American Heart Association Rapid Access Journal Report
American Heart Association

The body's involuntary processes may malfunction in shift workers and other chronically sleep-deprived people, and may lead to an increased risk of cardiovascular disease, according to new research in the American Heart Association's journal Hypertension.

Insufficient sleep and circadian rhythm (approximately 24-hour) disturbances both have been associated with adverse cardiovascular outcomes but the cause is unclear. To determine the impact of circadian rhythm disturbances on cardiovascular function in sleep-deprived people, researchers studied 26 healthy people, age 20-39. The study participants were restricted to five hours of sleep for eight days (sleep restriction) with either fixed bedtimes (circadian alignment) or bedtimes delayed by 8.5 hours on four of the eight days (circadian misalignment).

Researchers found sleep restriction combined with delayed bedtimes when compared to sleep restriction without delayed bedtimes was associated with:

an increased heart rate during the day for both fixed bedtimes and delayed bedtimes groups and even more so at night when sleep resctriction was combined with delayed bedtimes; reduced heart rate variability at night; an increase in 24-hour urinary norepinephrine excretion in the sleep resticted and delayed bedtimes group; and reduced vagal activity related to heart rate variability during deeper sleep phases (NREM); these deeper sleep phases have a restorative effect on cardiovascular function in normal individuals.

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